1. Field of the Invention
This invention relates to installing sections of horizontally laid underground piping using a coring rod to pull or push a coring knife horizontally through the site in which the piping is to be laid, and more specifically, to a device for supporting and guiding the coring rod and coring knife during tunnel diameter enlargement.
2. Description of Related Art
The Inventor has developed and patented methods and apparatuses for the laying of horizontally running underground piping, without having to first dig up the surface under which the piping will ultimately lie. Those methods and apparatuses are discussed and explained in U.S. Pat. Nos.: 5,498,106 and 5,505,558. The methods and apparatuses explained in said U.S.A. patents employ two pits. An entry pit on one side of the site under which the piping is to be laid, and an exit pit on the other side of the site under which the piping is to be laid.
In general terms, the method of installing horizontally laid piping underground, as taught by said U.S.A. patents, can be described as follows: An entry pit is dug on one side of the site under which the horizontally running underground piping is to be laid, and an exit pit is dug on the other side of the site under which the horizontally running underground piping is to be laid. From the entry pit, and at the correct depth, a pilot rod is pushed through the site into which the piping is to be laid, until the front end of that pilot rod emerges in the exit pit. Then, in the exit pit, two appropriately spaced and secured steering rods are attached near the front of the pilot rod, and one coring rod is attached near the front of the pilot rod, so that it is spaced and secured in the middle of the two steering rods. The pilot rod is then pulled back into the entry pit, causing the back end and length of the pilot rod to gradually emerge further and further into the entry pit, while simultaneously causing the three attached rods to enter deeper and deeper into the site, from their initial positions in the exit pit. The three attached rods create their own paths in the site as they are pulled through it toward the entry pit. Once the pilot rod has been pulled completely through the site, and is entirely in the entry pit, the other three rods have been pulled completely through the site, and are situated with their front ends in the entry pit, their lengths embedded in the site, and their back ends in the exit pit. Then, in the exit pit, a push-pull type coring knife is attached near the back end of the coring rod. Then, if the diameter of the piping to be laid, and if the soil of the site, is such that the tunnel can be dug with a single coring knife, and tunnel diameter enlargement will not be required, connecting a front cutting shield between the two steering rods, so that their back ends extend beyond the front cutting shield, and so that the front cutting shield is situated immediately behind the front cutting portion of the coring knife. Then placing a piece of the piping to be laid, inside the back of the front cutting shield so that it abuts the smaller internal diameter portion of the front cutting shield and cannot be moved forward without also moving the front cutting shield forward. Then placing a pulling cap over the back of the piece of pipe, so that its smaller internal diameter near its back edge abuts the back of the piece of pipe, and the pulling cap cannot be moved forward, without also moving the piece of pipe forward with it. Then attaching the pulling cap between the two steering rods, near their ends. Then by pulling the coring rod through the site, pulling the coring knife from the exit pit into and partly through the site, and pulling the two steering rods partly back through the site, thereby forcing the pulling cap, and the piece of pipe, and the front cutting shield partly through the site, behind the coring knife. Then continuing to pull the coring knife and the steering rods through the site, until the piece of pipe is entirely in the site. Then removing the pulling cap from the back of the piece of pipe, placing another piece of pipe immediately behind the inserted piece of pipe, so that it abuts up against its back end, and placing the pulling cap over the back of the second piece of pipe. Then again attaching the pulling cap, between the two steering rods, near their ends. Then pulling the coring knife further into the site, and pulling the two steering rods back through the site, thereby forcing the pulling cap, the two pieces of pipe, and the front cutting shield, further into the site, until the second piece of pipe is entirely in the site. Then again removing the pulling cap, adding another piece of pipe behind the second piece of pipe, again attaching the pulling cap behind the last piece of pipe, and again pulling the coring knife and steering rods further into the site. During the above process, removing the cored out soil from the back of the coring knife as necessary, either by pushing the coring knife back toward the exit pit, or by digging it out. Repeating the process of removing the pulling cap and adding new sections of piping, and then pulling them into the site, as the coring knife and the two steering rods are pulled further into the site, until the front cutting shield emerges into the open depression at the entry pit, and the piping has thereby been laid in the site. Then disconnecting the pulling cap from the steering rods, removing it from the back of the last piece of piping, pulling the steering rods out of the site, and removing the front cutting shield and coring knife.
However, in many situations the diameter of piping to be laid is to large for a large enough diameter tunnel to be dug, in the soil of the site, with a single coring knife. In those situations an initial tunnel is dug by using only a coring knife (without the pulling cap, or the sections of pipe, or the pipe installing apparatus) in the above described soil coring and pipe laying procedure. Then, after the initial tunnel has been dug, the coring rod is pushed back through the tunnel until its front end is in the exit pit. From the exit pit a first larger diameter coring knife is attached to the front end of the coring knife, and either the previously described pipe laying apparatus and procedure is employed, simultaneously with the digging of the larger diameter tunnel, or the larger diameter coring knife is pulled through the site by itself, thereby enlarging the diameter of the tunnel, and the coring rod is again pushed back through the tunnel until its front end is in the exit pit. From the exit pit a second larger diameter coring knife is attached to the front end of the coring rod, and the tunnel's diameter is enlarged a second time, or as the situations allows simultaneously with the second tunnel diameter enlargement, the previously described pipe laying process begins while the larger diameter tunnel is being dug.
As can be envisioned, whenever a tunnel diameter enlargement is taking place, whether it is with pipe being laid simultaneously, or it is simply in preparation for a second enlargement, when the front end of the coring rod with the coring knife attached is pushed entirely into the exit pit (as is necessary during the initial setup of the new coring knife, and during soil removal from the site by the pushing of the coring knife back into the exit pit) both the front end of the coring rod and the coring knife will fall to the bottom of the exit pit. When they fall to the bottom of the exit pit, the front end of the coring rod and the coring knife will dig into the bottom of the exit pit, and they will dig into the bottom end of the tunnel's exit pit opening. The coring rod and coring knife therefore have to be physically lifted up, and re-aligned with the central axis of the tunnel, before the coring rod can be pulled back through the site, to continue the pipe laying process.
One object of the present invention is to provide a means, which, during tunnel diameter enlargement, will substantially prevent the coring rod, and anything attached to it, from falling to the bottom of the exit pit each time the front end of the coring rod is pushed into the exit pit.
A second object of the present invention is to provide a means that will assist in maintaining the correct alignment of the coring rod and coring knife within the tunnel during tunnel diameter enlargement.
A third object of the present invention is to provide a means, that in certain of its embodiments, can assist in redefining the central axis of the tunnel during tunnel diameter enlargement.
A forth object of the present invention is to provide a means that accomplishes the other objects of the invention, and is durable.
A fifth object of the present invention is to provide a means that accomplishes the other objects of the invention, and is easy to use.